The present invention relates to railway rolling stock and, more particularly, to a car body for railway rolling stock and a method of fabricating the car body, with the car body being capable of being utilized at high speed travel.
In order to reduce the travel time between destinations in order to increase the volume of transportation, there has been a recent tendency to increase the travel speed of railway rolling stock; however, with such increase in travel speeds, various problems have arisen regarding the construction and fabrication of car bodies for railway rolling stock.
More particularly, with the railway rolling stock traveling at high speeds entering, for example, a tunnel, the external or outside pressure of the vehicle varies, with the larger external pressure being experienced when two vehicles pass each other in the tunnel. Consequently, it is imperative that the car body of the railway rolling stock be airtight so as to prevent any variation of the external pressure from being propagated to the interior of the vehicle; therefore, any variation of external pressure directly acts on the exterior portion of the car body. Thus, it has become necessary to provide a car body construction which is capable of enduring the variation in the external pressure to which the car body is exposed by virtue of increased travel speed.
Another significant factor which must be taken into consideration when considering high speed travel of railway rolling stock are the tracks upon which the railway rolling stock operates since the construction of the car body greatly affects the service life and condition of the tracks. Thus, there has been a demand to reduce the overall weight of the car body while nevertheless providing a sufficiently rigid car body construction capable of enduring the variation of external pressure acting on the exterior thereof as well as other problems resulting from the high speed travel.
In, for example, Japanese Utility Model Registration Application laid open no. 151309/1976, a circular car body is proposed to meet the stringent requirements occasioned by high speed travel of the railway rolling stock. In the proposed arrangement, the car body has a circular curved surface in which both side walls and the roof there are continuous on a flat underframe. By virtue of this construction, when the pressure caused by a variation in external pressure acts on the external portions of the car body, the tension within the surface acts on the outer plates since both the side walls and the roof are of a circular curved configuration. Thus, a bending moment outside the surface acting on the outer plate of both the side walls and the roof can be reduced. However, since the underframe is of a flat construction, when the external pressures act on the exterior of the car body, a greater bending moment upon the underframe and it has been necessary to have the underframe firmly constructed in order to compensate for such bending moment. While it is possible to increase the strength of the underframe and various associated members forming the underframe, in taking such an approach, the weight of the car body increases which is clearly not preferable in constructing high speed rolling stock.
Additionally, with high speed railway rolling stock which is powered by a large capacity electric drive means, the electric drive means are, for the most part, mounted on a lower surface of the underframe and, in particular, under the floor of the car body. Consequently, it is necessary to strengthen the underframe a sufficient amount so as to enable a support of the electric drive means which also leads to an increase in the weight of the underframe and, consequently, the car body.
The aim underlying the present invention essentially resides in providing a car body for a railway rolling stock which is lightweight and which is capable of withstanding a variation of external pressures applied on the car body.
An object of the present invention resides in providing a car body for railway rolling stock which is simple in construction and which can be easily fabricated.
Yet another object of the present invention resides providing an underframe for a car body of a railway rolling stock which has a sufficient strength to support the necessary components thereof while having a relatively light weight.
A still further object of the present invention resides in providing an underframe for a railway rolling stock which is simple in construction and which is relatively easy to manufacture.
Yet another object of the present invention resides in providing a method of fabricating a car body for railway rolling stock which facilitates the assembly of the car body.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings which show, for the purposes of illustration only, several embodiments in accordance with the present invention.